Stabilized non-adherent dressing



Dec. 17, 1968 G J. YEREMIAN STABILIZED NON-ADHERENT DRESSING v FiledDec. 6. 1966 INVENTOR. v GEORGE J. YEREMIAN BY United States Patent O3,416,525 STABILIZED NON-ADHERENT DRESSING George J. Yeremian,Greenwood, S.C., assignor to Parke, Davis & Company, Detroit, Mich., acorporation of Michigan Filed Dec. 6, 1966, Ser. No. 599,572 3 Claims.(Cl. 128156) This invention relates to surgical dressings and moreparticularly to a stabilized non-adherent dressing of an improved type.

Prior to the present invention, available dressings have in generalfailed to provide the intended free, non-adherent release from thehealing wound surface. One conventional dressing of the type inquestion, while not truly non-adherent, nevertheless achieves someimprovement with a construction in which the wound is contacted by asmooth perforated plastic film-gauze laminate. One such dressing isshown in US. Patent No. 2,923,298. More recently, a material withsuperior nonadherent properties has been developed. This superiormaterial, referred to below in detail, is a bonded laminate comprisingneedled webs of neutral organic plastic resin fiber and cellulosicmaterial. One :face of the laminate is comnosed of porous resin and thisserves as the non-adherent contact surface for the wound. One difficultywith this laminated material, however, is that it has -a relatively lowabrasion resistance. Also, it tends to delaminate when employed incertain types of dressing, particularly under stress of normal wear. Aconsequence of abrasion and delamination is that fibrous particles andother small particles can become dislodged from the dressing onto thewound site from which their later removal may be difficult and evendistressing.

It is an object of the present invention therefore to provide animproved non-adherent surgical dressing which is stabilized againstabrasion, delamination, etc.

It is also an object of the invention to provide an economicalnon-adherent surgical dressing which can be efficiently made in largevolume.

Another object is to provide a surgical dressing which can be safelyapplied to the wound site and kept there for indefinite periods underwidely varying conditions of use without risk of introducing extraneousdebris or particles to the wound site.

Still another object is to profide an improped surgical dressing whichcan readily be manufactured and packaged and thereafter distributed andused under sterile conditions, all the while retaining its intendedstructural integrity and aesthetic usefulness.

Other objects, advantages, and purposes will be seen in the followingdescription in reference to the accompanying drawings in which:

FIG. 1 is a plan view of a dressing according to the invention showing anon-adherent pad centered on an adhesive coated backing strip; and FIG.2 is a diagrammatic cross-section of the dressing of FIG. 1 taken online 2-2.

As seen in FIG. 1 the dressing of the invention comprises a backingstrip 19 coated with a suitable pressure sensitive adhesive 11 andsupporting a dressing pad 12. The pad and backing can be any of a widevariety of sizes, shapes, thicknesses, etc., for application to variousparts of the body, depending on particular requirements. The pad, as isshown and in fact as is conventional, will generally be spaced inwardlyfrom the margins of the backing strip 19, especially to permit sealingof the adhesive u on the skin around the pad edge 14 at all pointssurrounding the wound site. Although the adhesive surface of the backingis usually sufiicient for maintaining the'pad 12 in position, anoptional feature for this purpose is the provision of adhesion zones 133,416,525 Patented Dec. 17, 1968 "ice on the underside of the padindicated by the dotted lines along the longitudinal edges of the pad.The pressure exerted in securing the pad to the backing, in relation tothe thickness of the adhesive coating desirably should be such as totend to embed the edges of the cellulosic layer 16 within the adhesivelayer so as to restrain any random loose fibers from lateral movement.The type of adhesive means and backing employed is not critical. Usuallythese will be selected to simulate the properties of the skin in respectto flexibility, comfort, breathability, etc. If desired, they can bemoisture resistant or completely moisture impermeable.

The dressing pad 12 as seen in FIG. 2 extends "from the adhesive coatedbacking 19 at its edges 14 through the shoulder 15 to the pad face 20.The pad face 20 constitutes the surface intended primarily for directcontact with the wound. The pad is a laminate of two or more layersincluding a cellulosic layer 16 and a resin fiber layer 17. Thecellulosic layer is one having moisture absorption properties and iscomposed of a nonwoven mat or web of natural fibers such as cotton,artificial fibers such as rayon and mixtures of such fibers; the layersmay also contain other fibers or adjuvants such as an inertthermoplastic olefinic bonding fiber, e.g., polypropylene. The resinfiber layer is one permitting free flow to moisture and yet inert andcompatible with the wound surface. Any of various resins or mixtures ofresins which meet these requirements and which are thermoplastic, aswill be hereinafter described, will be satisfactory. The polyolefinssuch as polyethylene, polypropylene, etc., and other similar inert resinmaterials are suitable. Polypropylene is preferred for its ability towithstand steam sterilization. Other absorbent layers such as cellulosewadding, open weave textile and the like can if desired be included withthe cellulosic layer. The cellulosic layer and the resin fiber layer inthe pad according to the invention are secured together by needling andheat fusion. In the needling operation used to produce pads of thistype, the somewhat loose laminate is processed through a needlingmachine wherein the needles are injected through the laminate causingthe ensnared resin fibers to pass through the cellulosic layer at randomspaced points and the needled fibers 18 are heat fused in place. Fusionof the needled laminate is accomplished conveniently by passing theneedled laminate through pressure rolls with the resin fiber layer indirect contact with the heat surface to 'cause the fibers to soften,merge and rearrange to a substantially fiat, smooth integral poroussurface with the needled fibers likewise merged into the compressedcellulosic mat. Upon cooling, immediately after leaving the pressurerolls, the resin hardens and the compressed webs are thus transformedinto a single integrated laminate having the characteristics of a smoothdurable dense blanket structure.

For purposes of illustration, a suitable needled, pressure-secured padcan be made using a sheet of cellulose wadding (14 lbs/ream) laid overnon-woven web of rayon fibers (l /s length, 3 denier). A like web ofnonwoven polypropylene fibers is laid over the first web (to provide aweight ratio per unit area of 46 parts polypropylene, 21 parts waddingand 33 parts rayon) and the resulting laminate weighing about 4% ouncesper square yard is passed through a needling machine having 9 barbs perneedle to give between -120 needle perforations per square inch throughthe laminate. The

laminate is then fed through heat rolls for average exposure of /2second to 20 pounds per square inch and temperatures above 270 F.suflicient to fuse the resin and provide a smooth surface withnon-adherent characteristics.

The laminated pad material which is an improvement over priornon-adherent materials is nevertheless unsatisfactory, as indicatedabove, because of delamination, low resistance to abrasion, etc.According to the present invention, however, freedom from abrasiondamage, delamination and the like is advantageously obtained by thecombination of the pad and the adhesive coated backing strip 19 inconjunction with the shoulder 15. The shoulder can be formed in the padby any convenient forming means such as by pressing between stampingdies or passing the pad edge lengthwise through opposed embossingwheels, the surface contacting the non-adherent side in any case beingpreferably maintained at elevated temperature sufficient to soften thethermoplastic and thereby impress a permanent set at the edge 14 in theform of a shoulder. Pressure and heat means applied in this Way serve toanchor the resin and cellulosic fibers within the body of the pad andalso to render the pad more dense and rigid. Further, loose fibers,whiskers, etc., are desirably eliminated by this procedure, if necessaryby first spraying on or otherwise applying a suitable binder such asmethyl cellulose solution. The shoulder can extend around the margins ofthe pad, if desired. In this connection while it is important for theshoulder 15 to extend along and reinforce the major proportion of theedge 14, such a shoulder at the ends of the pad is not essential. Theinvention contemplates the provision of conventional release strips (notshown) overlying the adhesive layer and pad and a protective envelopesuited for sterilizing and maintaining the dressing in sterile conditionfor ultimate application to the wound site.

I claim:

1. In a surgical dressing having a non-adherent laminated pad with atleast one cellulosic layer and a porous resin fiber layer mutuallysecured by needling means, the improvement comprising an adhesivelycoated backing strip adhesively secured to the pad surface opposite thenon-adherent surface of the pad, the pad being spaced inwardly from themargins of the backing strip with sutficient adhesive surface exposedaround the pad to permit adhesive sealing at points surrounding a woundsite, and a marginal shoulder constituting areas of increasedcompression of the pad over at least a major proportion of the pad edge.

2. A surgical dressing according to claim 1 wherein the pad has anoblong shape and is provided with a marginal compression shoulder alongthe longitudinal edges of the pad.

3. A surgical dressing according to claim 1 wherein the pad comprises aneedled non-woven rayon-polypropylene fiber heat bonded laminate.

References Cited UNITED STATES PATENTS 2,923,298 2/1960 Dockstader etal. 128-296 3,122,141 2/1964 C-rowe 128-296 3,156,242 11/1964 Crowe128-156 3,229,691 1/1966 Crowe 128-156 3,331,728 7/1967 Lane 161-112ADELE M. EAGER, Primary Examiner.

US. Cl. X.R.

1. IN A SURGICAL DRESSING HAVING A NON-ADHERENT LAMINATED PAD WITH ATLEAST ONE CELLULOCIS LAYER AND A POROUS RESIN FIBER LAYER MUTUALLYSECURED BY NEEDLING MEANS, THE IMPROVEMENT COMPRISING AN ADHESIVELYCOATED BACKING STRIP ADHESIVELY SECURED TO THE PAD SURFACE OPPOSITE THENON-ADHERENT SURFACE OF THE PAD, THE PAD BEING SPACED INWARDLY FROM THEARGINS OF THE BACKING STRIP WITH SUFFICIENT ADHESIVE SURFACE EXPOSEDAROUND THE PAD TO PERMIT ADHESIVE SEALING AT POINTS SURROUNDING A WOUNDSITE, AND A MARGINAL SHOULDER CONSTITUTING AREAS OF INCREASED COM-